In the case of shooting video at the same time with dozens of cameras, confirming whether the video was successfully shot as intended with each camera involves playing back each file on the camera itself, or downloading and playing back files one at a time on a personal computer, which is time-consuming. Also, it is not known whether or not the moment (scene) that one absolutely wants to record is included in the video unless the video is played back. Furthermore, in the case of intending to shoot with the same settings, in some cases one may not notice when on-site that settings are different between cameras.
For example, PTL 1 discloses a technology that generates thumbnail image data for multiple still images and video, enabling one to search video content to find desired content in a short time. However, with this technology, one does not confirm whether or not the video was successfully shot as intended by each of multiple cameras.